Method and apparatus for guiding continuously cast strip

ABSTRACT

Method and apparatus for guiding metal strip continuously cast on the inside surface of a rotating ring through an open end thereof with minimum twisting comprises a plurality of pairs of guide rolls positioned and adjusted to cause the strip to travel in a spiral path of decreasing curvature on the surface of an imaginary cone, the axis of which passes through the ring.

United States Patent 1 191 Gerding 1 Sept. 4, 1973 [54] METHOD ANDAPPARATUS FOR GUIDING 2,450,428 10/1948 Hazelett 164/277 ONT CAST STRIP2,477,030 7/1949 Wuetig 164/84 X [75] Inventor: Charles ChristianGerding, FOREIGN PATENTS OR APPLICATIONS Pittsburgh, Pa. 528,359 7/1956Canada 164/87 22,943 8/1910 Great Britain.... 164/276 [731 AsslgneelJflmes & Steel Corporal, 1,177,758 1/1970 Great Britain 164/87Pittsburgh, Pa. 22 p Apt 2 19 2 Primary Examiner-R. Spencer AnnearAtt0rney-G. R. Harris and T. A. Zalenski [21] Appl. No.2 243,276

[57] ABSTRACT [52] U.S. Cl 164/87, 164/276, 164/282 Method and apparatusfor guiding metal strip continu- [51] Int. Cl 822d 11/12 ously cast onthe inside surface of a rotating ring [58] Field of Search 164/87, 276,277, through an open end thereof with minimum twisting 164/282 comprisesa plurality of pairs of guide rolls positioned and adjusted to cause thestrip to travel in a spiral path [56] References Cited of decreasingcurvature on the surface of an imaginary UNITED STATES PATENTSl-lazelett .1 164/277 X cone, the axis of which passes through the ring.

21 Claims, 3 Drawing Figures METHOD AND APPARATUS FOR GUIDINGCONTINUOUSLY CAST STRIP This invention relates to a method and apparatusfor guiding metal strip continuously cast on the inside surface of arotating ring. It is more particularly concerned with an apparatus forguiding such strip out of the ring with minimum deformation of the caststrip.

It is known to cast metal strip continuously on the inside surface of aring or drum which is rotated about its axis. Apparatus intended forcasting flat strip in this way is disclosed in I-Iazelett US. Pat. No.2,383,310 of Aug. 24, 1945. Apparatus intended for casting strip ofchannel-shaped cross-section in this way is disclosed in I-Iazelett US.Pat. No. 2,450,428 of Oct. 5, 1948. The first mentioned patent says thatthe solidified strip can be spiraled out through an open end of the ringbut neither describes nor illustrates apparatus therefor. It shows onlyapparatus for coiling the strip within the circumference of the ring,which presupposes a ring of rather large diameter. Such an arrangementwould allow the strip to cool in coil form, which would makestraightening difficult, and would necessitate interruption ofcontinuous casting to remove the coiled strip.

The principal problem in leading out strip through an end of the ring isto do so without excessive localized distortion of the cast metal.Although the strip is, of course, hot and can be bent to some extentwithout damage, its cast structure, particularly just as it separatesfrom the ring, can tolerate deformation only at a very limited rate.

The natural tendency of the cast strip as it separates from the ring isto fall away by its own weight, bending most severely at the region ofseparation where it is weakest. This bending, if uncontrolled, willoccur around a radius much smaller than is necessary or desirable foreductionof the strip from the ring. Even minor external mechanicalforces, such as those resulting from the pull of pinch rolls, likewisetend to concentrate the bending deformation at the weakest region of thestrip. Scrapers, where used, tend to do the same thing. Furthermore, anyforce applied outside the ring to lead the strip out of the ring tendsto twist the strip, principally in its weakest region.

It is an object of my invention, therefore, to provide a method andapparatus for continuously leading strip continuously cast on the insideof a ring out of an end of the ring with minimum bending and twistingdeformation of the strip. It is another object to provide such apparatusadapted to guide channel-shaped strip. It is still another object toprovide apparatus as above mentioned through which the strip is easilythreaded. Other objects will appear in the course of the description ofmy invention which follows.

7 I have invented a method and apparatus for guiding continuously caststrip out throughthe end of the casting ring which minimizes localizeddeformation, both bending and twisting. My apparatus decreases unequallythe curvatures of the two sides of the strip and so guides thesolidified strip from the ring into a spiral path of graduallydecreasing curvature or increasing radius on the surface of an imaginarycone. After the strip has cleared the ring, my apparatus equalizes thecurvatures of the two sides of the strip, so that it is traveling in ahelical path, from which it can be flattened to a horizontal plane.

My invention will be more readily understood by reference to theattached figures which illustrate an embodiment thereof presentlypreferred by me.

FIG. 1 is a perspective view of my apparatus, a portion of which isbroken away, illustrating its essential features. 7

FIG. 2 is an end elevation ofa guide unit of my apparatus comprising aguide roll pair and its mounting.

FIG. 3 is an elevation in cross-section of the apparatus of FIG. 2 takenon the plane 3-3 thereof.

In the figures, the strip 10 is solidified between the inner surface 11of a casting ring 12 and the outer surface 13 of a roll 14 which ispositioned within ring 12 near its lowermost point. Ring 12 is caused torotate in a clockwise direction as seen in FIG. 1 by means not shown,and its outside surface is cooled by means such as water sprays, alsonot shown, so as to extract heat from its inside surface 11. Likewise, acooling medium is circulated through roll 14 so as to extract heat fromits outside surface 13. Molten metal is supplied to the bottom portionof the ring 12 through flanges launder 15. Ring 12 is formed withinwardly directed inclined flanges 16 on each side so that a pool ofmetal is contained therebetween in its lowermost portion. Roll 14 isformed with beveled ends 17 which mate with fanges 16 so that thesolidified strip 10 is of channel-shaped cross-section.

The strip 10 solidified between ring 12 and roll 13 has approximatelythe same curvature as inside surface 11 of ring 12, which, of course, iscylindrical. In order to get it out through the open end of ring 12, itscurvature must be increased and it must be caused to move axially ofring 12. These changes in its path are brought about by passing itthrough successively positioned guide means or units to be described.These units are shown in perspective in FIG. 1 and in more detail inFIGS. 2 and 3.

The first guide unit 18 encountered by strip 10 as it is separated fromring 12 comprises an elongated mounting 27 from one face of whichproject parallel spindles 21 and 22 at its opposite ends. Spindle 21carries a freely rotatable roll 23 formed with outwardly projectinginclined flanges 24 at each end in the same manner and shape as insidesurface 11 of ring 12. Spindle 22 carries a freely rotatable roll 25having beveled ends 26 in the same manner and shape as the outsidesurface 13 of roll 14. From the opposite face of mounting 27 projects ashaft 28 joumaled in a plate 29 and passing through that plate. Shaft 28is positioned with its axis intermediate the axes of spindles 21 and 22,but nearer the axis of spindle 21 than that of spindle 22. Theprojecting end of shaft 28 carries a radially extending crank arm 30.Attached to plate 29 on the same side thereof as crank arm 30 is bracket31 in which is joumaled a trunnion ring 32 which holds a double- 'endedair cylinder 33 at one end thereof. The piston rod 34 of air cylinder 33is attached to crank arm 30 by pivot pin 35. Compressed air from asource not shown is introduced into the trunnion end of air cylinder 33through air line 37 and compressed air from the same'source isintroduced into the opposite end of air cylinder 33 through air line 38.Those air lines are connected to a four-way valve, not shown, by meansof which the air can be supplied to either end of the air cylinder asdesired.

Guide unit 18 is positioned inside ring 12 with roll 23 between theinside surface 11 of ring 12 and the path of separated cast strip 10.Roll 25 is on the opposite side of cast strip 10. The guide unit 18 ispositioned so as to bend the cast strip inwardly and increase itscurvature. Unit 18 is also positioned so that the increase in curvatureof strip 10 on its side adjacent the exit end of ring 12 is somewhatless than the increase in curvature of the strip on its other side. Thesecond and third guide units 19 and 20 respectively are of the sameconstruction as guide unit 18. The three units 18, 19 and 20, each ofwhich is at least partially inside ring 12, are positioned so that theportions of the successive units which are inside the ring aresuccessively smaller. They are likewise positioned so that the path theyimpart to the strip 10 is a spiral around an imaginary cone, the axis ofwhich passes through ring 12. Diametrically opposite elements of thisimaginary cone are shown as dotted lines 40 and 41 in FIG. 1. The apexangle of the cone is only a few degrees and, as shown in FIG. 1, thebase of the imaginary cone adjoins the exit end of ring 12. Element 40is the first element of the cone of evolution encountered by the strip.It lies near to the inside surface 11 of ring 12 and lies on the surfaceof strip 10 shortly after its separation from ring 12 but is not atright angles to the edges of strip 10 by a few degrees.

The guide units l8, l9 and 20 previously mentioned are all positioned atleast partially within the upper half of ring 12. The curvature impartedto the strip by those units causes it to continue to travel through afurther angular distance bringing it around into an approximatelyhorizontal plane at or near the lowermost portion of ring 12. Pinchrolls 43 and 44 disposed above and below the strip path are positionednear the lowermost portion of ring 12 so as to equalize gradually thecurvatures of the two edges of the strip and change the path of travelof strip 10 gradually from a spiral on an imaginary cone to a circle. Atthe same time they decrease those equalized curvatures to zero, ifdesired, so as to produce strip the central portion of which is flat.Those pinch rolls are driven by means not shown.

The guide units 18, 19 and 20 are mounted on a framework, not shown,which projects into the open end of ring 12 opposite the end from whichthe strip 10 is lead out. The individual units 18, 19 and 20 areattached to this framework by affixing their respective mounting plates29 to the framework at the angles required to guide the strip as hasbeen described above. For this purpose, the framework or the mountingplates are provided with conventional adjusting means, such as adjustingscrews, not shown.

At the commencement of operations of my apparatus, the rolls 23 and 25of each unit l8, l9 and 20 are set so that the plane common to theirparallel axes is more or less at right angles to the strip path. Thisprovides a gap between rolls 23 and 25 to maximum width. The rolls areset in this position by admitting air to air cylinder 33 through airline 37. A dummy or starter strip approximately equal in width to strip10 to be cast but somewhat thinner is placed with one end in ring 12 atits lowermost portion and is trained under roll 14 and through units 18,19 and 20 and pinch rolls 43 and 44. Molten metal is then led into thelowermost portion of ring 12 through launder and ring 12 is caused torotate. Pinch rolls 43 and 44 are likewise started up. The first moltenmetal solidified between ring 12 and roll 14 freezes to the end of thedummy strip and is lead around through the guide units thereby. Whensolidified strip 10 is in the guide units air is admitted to air line 38and allowed to exhaust through air line 37 so causing piston rod 34 tomove to the right in FIG. 2 and rotate rolls 23 and 25 into theirposition of minimum gap as shown in FIG. 1. The centerline of shaft 28is spaced from roll 23 a distance of a little more than the thickness ofcast strip 10, so that rotating shaft 28 to open or close the gapbetween rolls 23 and 25 does not greatly alter the upper limit of thestrip path.

As I have mentioned, the apex angle of the imaginary cone is small anddesirably is as small as possible. Its minimum value is dependent on therelation between the width of the cast strip and the inside diameter ofthe ring through which it must be led out. I have constructed successfulapparatus with values of this angle between about 6 and about 15.

It is also desirable to keep the angular path of travel of the strip onthe imaginary cone as short as possible, as the angular range over whichthe strip will lie in full contact with a conical surface is limited.This range depends on the apex angle of the cone. It is generallydesirable to bring the strip out more or less horizontally through pinchrolls 43 and 44. As the molten metal pool occupies the bottom portion ofthe ring 12, roll 13 must be down stream from the metal pool, clockwisein FIG. 1, and the chilled strip separates from ring 12 and roll 13somewhat down stream of that roll. Thus the available angular path oftravel is something less than 360. I find it possible to lead out thestrip in the way here disclosed in an angular path of travel as short asabout 315.

The path of the strip as it leaves pinch rolls 43 and 44 is not parallelto the vertical plane of the end of ring 12 but is inclined thereto atan angle which depends on the apex angle of the imaginary cone and theangular length of the strip path on the cone.

My apparatus may be modified in accordance with the requirements of thestrip being cast. If a large casting ring is employed, it may bedesirable to drive one or both of guide rolls 23 and 25 in some or allof the guide units. If very wide strip is to be cast, the apex angle ofthe cone may be somewhat larger than the values previously mentioned. Itmay be desirable under some conditions to use fixed auxiliary guidesrather than a dummy strip to enter the cast strip into the guide units.Other modifications will occur to those skilled in the art of stripcasting.

I claim:

1. Apparatus for guiding metal strip continuously cast on the insidesurface of a rotating ring out of the ring through an open end thereofcomprising guide means positioned circumferentially of the ring andadjusted to increase gradually the curvature of the strip as it isseparated from the ring, the curvature of the inside edge beingincreased more than the curvature of the outside edge, then to decreasegradually those curvatures so that the strip is caused to travel in aspiral path disposed on the surface of an imaginary cone the axis ofwhich passes through the ring.

2. Apparatus of claim 1 including guide means positioned and adjusted toreduce gradually and equalize those curvatures as the strip passes outof the ring.

3. Apparatus of claim 1 including guide means positioned and adjusted toreduce the curvature of the strip to zero after the strip has passed outof the ring.

4. Apparatus of claim 1 in which the guide means are positioned andadjusted to lead the strip from contact with the ring surface out of thering in an angular travel of less than about 360.

5. Apparatus of claim 1 in which the apex angle of the cone is betweenabout 6 and about 6. Apparatus of claim 1 in which an element of theimaginary cone lies on the surface of the strip approximately where itis being separated from the ring.

7. Apparatus of claim 1 in which the guide means comprise a plurality ofpairs of rotatable rolls, each pair being mounted with the roll axesparallel to and spaced from each other so that the strip passes betweenthe rolls of a pair.

8. Apparatus of claim 7 including at least three pairs of rolls.

9. Apparatus of claim 7 in which at least the first pair of rolls ispositioned at least partially within the rotating ring.

10. Apparatus of claim 7 in which the first and second pairs of rollsare positioned at least partially within the rotating ring, with thesecond pair being positioned inside the ring to a lesser extent than thefirst pair.

11. Apparatus of claim 7 in which one guide roll is provided withflanges and the other guide roll is provided with beveled ends.

12. Apparatus of claim 7 in which at least one pair of rolls iscantilevered from a mounting which is adjustable pivotally about an axisparallel to the roll axes and positioned therebetween.

13. Apparatus of claim 12 including remotely controllable means forrotating the mounting about its pivot.

14. Apparatus of claim 12 in which the axis of the mounting pivot iscloser to one roll of the pair than it is to the other roll of the pair.

15. Apparatus of claim 14 in which the uppermost roll is closer to theaxis of the mounting pivot.

16. A method for removing metal strip continuously cast on the insidesurface of a rotating ring from the ring through an open end thereofwhich comprises separating the strip from the ring, increasing thecurvature of the strip as it is separated from the ring in a manner suchthat the curvature of the strip edge furthest away from said open end ofthe ring is increased more than the curvature of the strip edge nearestsaid open end of the ring and gradually decreasing said curvatures sothat the strip travels in a spiral path disposed on the surface of animaginary cone having an axis which passes through the ring 17. Themethod of claim 16 which includes gradually both reducing and equalizingsaid curvatures as the strip passes out of the ring.

18. The method of claim 16 which includes reducing the curvature of thestrip to zero after the strip has passed out of the ring.

19. The method of claim 16 which includes leading the strip from contactwith the ring surface out of the ring in an angular travel of less thanabout 360.

20. The method of claim 16 in which the apex angle of the imaginary coneis between about 6 and about 15.

21. The method of claim 16 in which an element of the imaginary conelies on the surface of the strip approximately where it is beingseparated from the ring.

1. Apparatus for guiding metal strip continuously cast on the insidesurface of a rotating ring out of the ring through an open end thereofcomprising guide means positioned circumferentially of the ring andadjusted to increase gradually the curvature of the strip as it isseparated from the ring, the curvature of the inside edge beingincreased more than the curvature of the outside edge, then to decreasegradually those curvatures so that the strip is caused to travel in aspiral path disposed on the surface of an imaginary cone the axis ofwhich passes through the ring.
 2. Apparatus of claim 1 including guidemeans positioned and adjusted to reduce gradually and equalize thosecurvatures as the strip passes out of the ring.
 3. Apparatus of claim 1including guide means positioned and adjusted to reduce the curvature ofthe strip to zero after the strip has passed out of the ring. 4.Apparatus of claim 1 in which the guide means are positioned andadjusted to lead the strip from contact with the ring surface out of thering in an angular travel of less than about 360* .
 5. Apparatus ofclaim 1 in which the apex angle of the cone is between about 6* andabout 15* .
 6. Apparatus of claim 1 in which an element of the imaginarycone lies on the surface of the strip approximately where it is beingseparated from the ring.
 7. Apparatus of claim 1 in which the guidemeans comprise a plurality of pairs of rotatable rolls, each pair beingmounted with the roll axes parallel to and spaced from each other sothat the strip passes between the rolls of a pair.
 8. Apparatus of claim7 including at least three pairs of rolls.
 9. Apparatus of claim 7 inwhich at least the first pair of rolls is positioned at least partiallywithin the rotating ring.
 10. Apparatus of claim 7 in which the firstand second pairs of rolls are positioned at least partially within therotating ring, with the second pair being positioned inside the rinG toa lesser extent than the first pair.
 11. Apparatus of claim 7 in whichone guide roll is provided with flanges and the other guide roll isprovided with beveled ends.
 12. Apparatus of claim 7 in which at leastone pair of rolls is cantilevered from a mounting which is adjustablepivotally about an axis parallel to the roll axes and positionedtherebetween.
 13. Apparatus of claim 12 including remotely controllablemeans for rotating the mounting about its pivot.
 14. Apparatus of claim12 in which the axis of the mounting pivot is closer to one roll of thepair than it is to the other roll of the pair.
 15. Apparatus of claim 14in which the uppermost roll is closer to the axis of the mounting pivot.16. A method for removing metal strip continuously cast on the insidesurface of a rotating ring from the ring through an open end thereofwhich comprises separating the strip from the ring, increasing thecurvature of the strip as it is separated from the ring in a manner suchthat the curvature of the strip edge furthest away from said open end ofthe ring is increased more than the curvature of the strip edge nearestsaid open end of the ring and gradually decreasing said curvatures sothat the strip travels in a spiral path disposed on the surface of animaginary cone having an axis which passes through the ring.
 17. Themethod of claim 16 which includes gradually both reducing and equalizingsaid curvatures as the strip passes out of the ring.
 18. The method ofclaim 16 which includes reducing the curvature of the strip to zeroafter the strip has passed out of the ring.
 19. The method of claim 16which includes leading the strip from contact with the ring surface outof the ring in an angular travel of less than about 360* .
 20. Themethod of claim 16 in which the apex angle of the imaginary cone isbetween about 6* and about 15*.
 21. The method of claim 16 in which anelement of the imaginary cone lies on the surface of the stripapproximately where it is being separated from the ring.